Can anyone help… LV & tellecomms ducting, shared trench?

[PTL123]

Is it okay to lay ducting housing LV cable in the same trench as ducting housing Tellecomms?

I’ve always been told that this is not okay but my new company seem to think it’s fine.

Thanks for any help with this, if anyone has any link to official regulations on the subject it would be greatly appreciated.

Apologies if this has been covered elsewhere but I’ve been scouring the internet and can’t seem to find an answer anywhere.

 

[littlespark]

AFAIK, allowed in the same trench, but not the same duct.

May need to be a certain distance between each other in the trench… ie, not touching, 300mm apart or something.

 

[pc1966]

It also depends on the cables. Generally if they are SWA or shielded (e.g. Flexishield, FP200, etc) then you can run other stuff quite close without problems, but generally I would always put telecoms in a separate duct even if in the same trench.

BT/Openreach have some specific guidance but from memory even with shielded cables they have a minimum of a couple of mm so really it would need separate duct to achieve this.

Of course if it is fibre then no electromagnetic issues at all, but some contractor (understandably) don't want to be messing about with anything sharing dangerous voltages even if the fibre is nominally insulating throughout.

 

[pc1966]

Page 16 of this has 295mm between Openreach duct and any power duct:

https://www.openreach.com/content/dam/openreach/openreach-dam-files/images/fibre-broadband/fibre-for-developers/guides-and-handbooks/oct-2019-update/amends/Copper%20handbook%20V3.1%20web.pdf

It also says of in-home wiring:

A minimum of 50mm between telephone cables and power cables should be left throughout. Where this isn’t practical, telephone and power cables must be separated by an acceptable divider (i.e. of rigid, non-conducting material)